Production of suppression layer photocells



Oct. 29, 1935. RQTHER 2,619,096

PRODUCTION OF SUPPRESSION LAYER PHOTOOELLS Filed July 7, 1933-IIIIIIIIII Franz R t/ver attorney ufacturing a cell of Patented Oct.29, 1935 UNITED STATES PRODUCTION OF SUPPRESSION LAYER PHOTOCELLS FranzBother, Paris, France Application July 7, 1933, Serial No. 679,285 InGermany July8, 1932 6 Claims.

This inventionrelates to improvements in suppression layer cathodes forphoto cells and the like and to a method for manufacturing the same.

An object of the invention is to provide a cell of the aforementionedcharacter having improved sensitivity and efficiency. 7

Another object is to provide a cell of great durability.

Another object is to provide a cell which can be easily manufactured.

Another object is to provide a method for manthe aforementionedcharacter.

Other objects and advantages will hereinafter appear.

An embodiment of my invention'will be explained in the followingdescription with reference to the appended drawing in which Figure 1 isa cross sectional view of the construction of a cell as used heretofore,while Fig. 2 is a similar view of a cell constructed in accordance withmy invention.

The suppression layer photo-cells were hitherto produced, for example inthe .case of the coppercuprous oxide ,cell, by heating a metallic copperplate to about-1020 C. for some time in a furnace in the presence ofoxygen.

The known suppression layer photo-cell is illustrateddiagrammatically insection in Fig. l.

The cell removed from the furnace shows on its surface copper oxidewhich is removed by suitable processes, so that the cuprous oxide layer3 is exposed which is located under the copper oxide and has grown onthe mother copper I. The very thin hypothetic suppression layer 2 whichis permeable for the electrons only in one direction, is situatedbetween the cuprous oxide layer 3 and the metallic copper support(mother copper) I. The mother copper plate I serves as one of theelectrodes of the finished suppression layer cell, whereas usually athin metal layer 4 applied on the cuprous oxide layer 3 by knownprocesses, such as cathode atomizing, serves as second or counterelectrode.

It has now been found that the photo-electric effect of such suppressionlayer photo cells can be considerably increased if the metallic copperplate I, in the case of a copper-cuprous-oxide cell, is coated with alayer 5 of another metal as shown in Fig.2 before being brought to ahigh temperature. The coating 5 may be applied to the mother copperplate I by cathode atomizing. electrolysis, by a spraying process or byany other suitable process. If, for example, a copper plate I is coatedwith a gold layer 5 before being brought to a high temperature, thisgold layer 5 remains on the copper after the finishing of the cell or ispartly alloyed with the latter at its sur: face and the cuprous-oxidelayer 3 has formed over the gold layer 5. Consequently over the 5 mothercopper I there is besides the known thin suppression layer 2 also thegold or gold alloy layer 5 and above this the cuprous oxide layer. Sucha suppression layer photo-celhhowever, as compared with a similarcellbut without the gold layer 5 previously applied onto the copper I, showsabout 10 times greater photo-electric effect or a ten times greaterenergy yield under otherwise similar conditions.

The metal layer 5, applied to the metallic copper I, may be extremelythin, so thin that it is translucent. Such a cell also presents theadvantage over the known cells as regards production, that the cuprousoxide 3 uniformly covers the whole surface of the cell and chipping offof a portion of the cuprous oxide layer when removing the cell from thefurnace or during the cooling, as often happens in the production of theknown cells, being .avoided. The copper plate I, in the case ofcopper-cuprous oxide cells, may also be covered with two or more thin,superposed metal layers 5 before it is brought to a high temperature.

By this process other metals besides copper may be employed as mothermetal I for producing suppression layer photo cells. The copper I underthe applied gold layer 5 diff-uses into and through the thin gold layerat the production temperature of the cell, so that the oxygen compoundsof'the copper then form on the gold or gold alloy layer 5.

The new'process is particularly practical if the mother metal, on whichthe thin metal coating 5 is applied, is not a pure metal but a metalalloy which may consist of two or more components. 49 Precious metals.are particularly suitable as coating metal 5 in the sense of theinvention, but any of the metals may be employed except the metals ofthe alkali group. If, however, more than one coating layer 5 is to beemployed, thin layers of metals which can easily oxidize, may be appliedover or under the precious metal layer. Fig. 2 must be regarded merelyas a diagrammatic view.

I claim:

1. In the process of producing suppression layer cathodes for photocells and the like, comprising a copper base and a coating of an oxidethereof, the step which consists in coating said base with a thinlayerof I another metal not belonging to the alkali group of metals andthereafter heating the so coated base to thereby cause copper to difiuseinto and to form an alloy with said other metal and further to oxidizeat least part of the copper so diffused to form said oxide coatingoverlying said alloy.

2. In the process of producing suppression layer cathodes for photocells'and the like, comprising a copper base'and a coating of an oxidethereof, the step which consists in coating said base with a thin layerof a precious metal and thereafter heating the so coated base to therebycause copper to difiuse into and to form an alloy with said preciousmetal and further to oxidize at least some of, the copper so diffused toform an oxide of said copper overlying the surface of said alloy.

3. In the process of producing suppression layer cathodes for photocells and the like, comprising a copper base and a coating of an oxidethereof, the step which consists ,in coating said base'with a pluralityof successive thin layers of different other metals not belonging to thealkali group of metals and thereafter heating the so coated copper baseto thereby cause copper 'to diifuse into and to form alloys with saiddifferent other metals and further to oxidize at least some of thecopper so diffused to form an oxide of said copper overlying saidalloys.

4. A suppression layer photo cell comprising, in combination with acopper base and a layer of an oxide thereof, an alloy of said copper andanother metal not belonging to the alkali group of metals interposedbetween said copper base and said layer and adhering to said copper baseand said oxide by an inter-molecular-bond.

5. A suppression layer photo cell comprising, in combination with acopper base and a layer of anoxide thereof, an alloy of said copper anda precious metal interposed between said copper base and said layer andadhering to said copper base and said oxide by an inter-molecular bond.

6. A suppression layer photo cell comprising, in combination a copperbase and a layer of an oxide thereof, a plurality of thin layers ofalloys of different other metals not belonging to the alkali group ofmetals and said copper, said layers being interposed between said copperbase and said oxide layer, said copper base and said layers adhering toone another at their respective boundaries by an inter-molecular bond.

FRANZ ROTHER.

